Mars getting pounded

Grypd · 2006-12-12 10:43:49

The planet Mars is a glutton for punishment.

Scientists have found no less than 20 new craters etched into the red planet’s surface from space rocks that pummeled Mars within the last seven years [image].

“If you were to live on Mars for about 20 years, you would live close enough to one of these events to hear it,” said researchers Michael Malin, who led the study. “So there’d be a big boom and you’d know there was an impact crater.”

This indicates that when we get to Mars that we have to seriously consider thickening the atmosphere quickly. And until then we will have to have a very effective Skywatch

nickname · 2006-12-13 17:37:15

Grypd,

Hmmmm! if that is a typical happening for Mars, then its unlikely that the surface material and gasses expelled from impacts will be of much use for terra forming Mars.

If the surface material and deeper was full of frozen co2 and h20, them mars probably would have been terra formed from natural impacts.
This might be a big blow to plans for a green mars, and might be a good indication that Mars has little or no permafrost of any kind below the surface.

Grypd · 2006-12-14 05:12:16

Not enough impacts and certainly not of enough power.

If it was pure snowball type asteroids then that would be a different matter.

nickname · 2006-12-14 12:13:19

Grypd,

I was thinking more in the terms of the last 500 million or so years.
Every possible place on Mars a mile or more deep must have had its frozen gas/water released from impacts, even if they are modest ones at a dozen a year.

If the impacts are a typical year for Mars then i doubt if any C02 or H20 exists other than the poles.

Might even be why the frozen H20/C02 deposits are on the poles, simple atmospheric gas freezing from impacts makes an interesting scenario for the pole frozen gas\water accumulation.

Hope I'm wrong because it would make Mars a very resource depleted place other than the poles.

Grypd · 2006-12-14 12:54:44

These where small scale impacts and yes they would have released water if they hit the right spot but the water is just as likely to refreeze at the poles or settle onto the permafrost layer again.

These are not powerful enough impacts to remove atmosphere in sufficient amounts and there is also likely to be atmosphere gained by volcanic action which from the size of those shield type volcanoes we do know exist. I wonder if we have the more powerful supervolcanoes present too?

Still they are impacts and they cause localised issues. They could throw a lot of dust into the atmosphere and make a dust storm strengthen.

nickname · 2006-12-15 05:16:05

Grypd,

The Viking landers detected no seismic activity on Mars, so volcanic activity is either non existent or very episodal.

Since these small impacts make it directly to the surface of mars due to its thin atmosphere, a good experiment to find out when mars was more volcanically active is to search back for the oldest small impact craters.

At the age of the oldest small impactors is about the time mars became volcanically inactive and the atmosphere wasn't being replenished, or was thin enough for very small impactors to reach the surface.

That would give us a good idea of what mars has been doing and for how long, or at minimum how long mars has been how it is now.

If that number comes back a billion years then we can bet that most of the pole accumulation is from impact gas accumulation.
If it is 100 million or so years then the pole accumulated probably was started when the surface water stared to freeze.

My guess for the poles to slowly accumulate frozen h20 and slowly deplete it from other places on mars is hundreds of millions of years.

Interesting whatever result we get.

RickSmith · 2007-03-03 03:58:36

Hi all,

"Malin said that it was by chance Edgett spotted an image with a new crater and recalled a similar view taken years earlier by the MGS orbiter. Their subsequent survey found the new craters, which range in diameter from seven feet (two meters) to 486 feet (148 meters), and an average impact rate of about 12 per year."

My guess would be that most of these 12 impacts / year will create craters less than 50 meters across. That will be enough to move the water into vapor, but it will simply frost out again.

In the book "Mars: A Warmer Wetter Planet" by Jeffry S. Kargel, ISBN 1-85233-568-8, (c) 2004, he makes a strong argument for active rock glaciers (fed by winter frosts) on Mars. Mars is dry because it is cold, not because there is not a lot of water on it.

Thanks Grypd for posting such an interesting link!

Warm regards, Rick

nickname · 2007-03-03 05:38:16

RickSmith,

The trouble with the 12 impacts a year if mars is wet underneath, is where is the thick layer of snow covering the planet?

12x 100 million years or 1 billion years.
Even with a small release of h20 from each impact, if the h20 doesn't migrate to the poles then mars should be covered in snow?

Either mars is so dry under its surface that impacts release near nothing in h20,or all the h20 has migrated already.

If we guess at mars being like it is for 1 billion years, that is 12 billion small impacts.
More than enough to vaporize all the h20 everywhere on the planet a few hundred feet down.
That is not even accounting for the larger rarer impacts.

No snow on the surface probably = no water under the surface.

RickSmith · 2007-03-03 14:33:27

Hi Everyone, nickname.

The short answer is, covered by dust and rock.

Also it is not all at the pole. On page 216 of "Terraforming: Engineering Planetary Environments" Martyn J. Fogg points out that ice is stable year round above 40 degrees of latitude. (It can be stable closer to the equator, but it must be protected by a covering of rock and dust.)

On page 361 of "Mars: A Warmer Wetter Planet" it says (talking about the glacier like land forms in the Noachis Terra region):

"... The rare, exceptional fresh-looking fields of narrow crevasses in some of the lobate debris aprons in Argyre and Noachis Terra, however, indicate that some of these icy flows have been active, albeit weakly, within the past few decades or centuries; sublimation would have widened or subdued the crevasses if exposed for longer than that at their latitudes and with their [the rock glaciers] slope and aspects."

Read Dr Kargel's book. It has overwhelming evidence that there is a lot of ice frozen under the ground. It has persuasive evidence that some rock glaciers are still active, fed by seasonal frost build up at the head of the glacier. (Admittedly these glaciers are flowing 10,000 times slower than they do on Earth because of the lower gravity and much slower build up of ice.)

Warm regards, Rick

nickname · 2007-03-03 18:09:56

RickSmith,

It's a puzzle for sure.

Those little thumps on Mars even though they only make 50 ft wide craters should vaporize water around that impact site for another 50-100ft down and surrounding the impact zone.

On Mars that water at the atmospheric pressure doesn't ice out, it contributes directly to the atmosphere in the short term.
Only icing out as it cools, impacts on Mars should turn frozen h20 directly into gas.

The mystery is where is all that ice from at least 100 million years on impacts?
It cant be below the surface, because all forms of gas should be freed to the atmosphere with the heat from each impact.

I agree Mars has ice all over the place, but in such limited quantities that it maybe only accounts for a few 100 years of impacts.

It's something interesting to think about, really makes you wonder if all that expected frozen h20 will be under the surface or not.
Or maybe just not in the first 100ft depth.

RickSmith · 2007-03-03 18:26:30

Hi nickname,
I don't really understand your question / argument. As water is vaporized by small impacts it eventually cools and frosts out all over the place including old impact craters. Moisture in the top parts of the soil may or may not sublime. If it does, it may well work its way deeper into the soil where it is stable.

In any case it can be buried by dust and sand.

With a little ground pressure and salts (to create brines with low freezing temperatures) during the summer moths some of this frost can turn liquid and work its way deeper.

I expect to find water frozen as permafrost inside old craters as well as non-cratered terrain.

Warm regards, Rick

nickname · 2007-03-04 07:28:15

RickSmith,

The bar pressure on Mars is to low for water to exist as liquid, melted ice becomes gas in a semi violent reaction.
Even water that is 50% salt cant stay as liquid, even liquid co2 on mars would gas out.

Its possible for frost to reform on the surface of mars after each impact, but only in the short term.
Mars acts like a big freeze dryer, most of the frost should return to the atmosphere quite quickly.
This might be the mechanism that forms the pole water ice deposits over millions of years, simply because it's cold enough at the poles for water ice to stay in a more permanent freeze.

In my opinion not much of the frost will have a chance to sublimate to deeper levels, no real mechanism exists on mars to allow it other than dust cover.
Some of the frost might make it as deep as the dust covers is, but on Mars the constant global dust storms should expose most of that frost to the surface periodically.

Mars in my opinion will be freeze dried for the first 100ft or so, after that depth we might find frozen water reserves.
Some of the cooler latitudes on mars might be an exception, those places that have been below 0c for eons and lucky enough not to be hit with small impactors that locally heat thing up over the last billion years.

Just my thoughts though, but if i was going to mars to look for water i would settle near the poles or get a deep well dug

RickSmith · 2007-03-04 14:05:00

Hi Everyone, nickname.
I do not argue that liquid CO2 won't explode into vapor on Mars. It is a long way from its triple point.

There have been numerous reports in the astronomy news about signs of liquid water on modern Mars. Examples include new gullies on crater walls that show stains (such as might be made by a liquid). I am going on a business trip in a few minutes and I don't have time to hunt down references, sorry.

Brines do not boil furiously on modern Mars, they evaporate. If there is a skim of ice on top of them they evaporate slowly or, if the conditions are right, they freeze solid.

In anycase the argument about rock glaciers is not dependent on liquid water, they grow because of frost. We know that there is frost on Mars because the Viking landers and others have seen it.

The reason why Mars' atmosphere is so dry is not because Mars lacks water. It is because it is so cold.

I read somewhere that if a book does not shake you up, at least a little bit, then your time has been wasted. (By that standard, I've wasted a LOT of time.) I think you might enjoy "Mars: A Warmer Wetter Planet." It would certainly give you more amunition.

(We will likely still be arguing, "but on a higher level about more important things".)

Warm regards, Rick.

RickSmith · 2007-03-17 03:44:23

Hi all,
The problem with "Mars: A Warmer Wetter Planet" is that most people and most libraries don't have it. (Ask your local library to get a copy!) However on page 10 of "National Geographic" Jan 2004 they have a orbital picture of what looks like a martian rock glacier complete with flow lines and talus piles at the bottom.

Warm regards, Rick

nickname · 2007-03-17 07:39:34

RickSmith,

I've read a bit of "A Warmer Wetter Planet".
All speculation though that Mars is really a wet place when we get below the surface layer.

I still look at the poles on a freeze dried planet and wonder how they stay as ice.
With all that radiation UV etc hitting the pole ice, it should be slowly removed from the poles.

As soon as it's in vapor form the UV should break the h20 bonds, hydrogen being such a light gas should quickly work its way off the planet leaving lots of free 02 around.

The peroxide guess/data from Viking seems to point to that being the case, but levels of 02 should be very high if the poles have been in existence for a long period of time.

Free 02 should be much higher in the atmosphere also if the poles have been in existence for 100 million years or more.

Mars for sure is an interesting place, trying to figure the planetary mechanics out will probably give us a real picture of Mars with little speculation.

Hopefully Mars won't turn out to be an extreme desert 100s of meters deep everywhere but the poles, due to freeze drying and small impactors over millions or billions of year

Joseph_Dunphy · 2007-04-08 05:14:01

I think I can see what nickname is trying to say, and perhaps I can give him (or her) a missing piece of the puzzle.

Let's say that earth was cold and bone dry at the surface, with permafrost near the surface, and frequent powerful meteor impacts, each generating large amounts of heat on impact. The heat would generate steam, which would rise up out of the impact crater, cool and condense back as snow or frost on the surface. Why, then, wouldn't we see similar frost on the surface of a Mars with ice under the surface?

Because Mars, unlike Earth, lacks an ozone layer, and ultraviolet light reaches the Martian surface at almost the full strength one would find it at in space. UV photons are energetic enough to break the bonds in water molecules, so illuminating water ice under martian conditions with the high UV levels found there will result in the liberation of elemental hydrogen, which Mars hasn't a deep enough gravitational well to hold onto, and which won't find much of anything to react with on the way out. A little free oxygen is liberated in the process, which then is removed from the atmosphere through the weathering of rocks on the surface which, on Mars, is not counterbalanced through volcanic outgassing, as it is on Earth. The hydrogen ends up gone and the oxygen ends up bound.

That's where your surface frost went.

nickname · 2007-04-08 07:58:00

Joseph_Dunphy,

I'm glad someone got an idea of what i was saying.

I do see the ability for the weathering of rocks to remove some or most of the free 02 over a few million years.
It's a good explanation for the no frost accumulations on Mars.
After that first few meters is soaked with free 02 what happens to the other 90 million or up to 2 billion years worth of free 02?

It's a puzzle to make sense of where it could be if the poles have been around for a long time.
Maybe we are wrong about the H20 ice quantity on Mars, maybe it's more C02 ice than we expect?
That would make for a simple solution to the free 02 problem, H20 was never in huge quantities so it didn't accumulate much free 02.

RickSmith · 2007-04-09 01:50:52

Hi everyone, nickname.

It is almost certain that Mars has lost water because it has been broken up by ultra violet light. However this takes millions to billions of years, and buried water is pretty much immune.

The iron in the planet's crust is red (likely) because of the oxygen released from water this way (unless there were plants on Mars once). The oxygen oxidized the local minerals making giving iron the red 'rust' colored valence state.

However, the water loss is slow and Mars gets more volitiles from carbonaceous chondrite meteors, comets and from volcanic eruptions. Is the water loss from H2O dissociation slow enough? The proof is in the pudding. We have detected a lot of hydrogen in the top meter of the soil at the high latitudes (40 degrees and above) so obviously the dissociation is slow enough that plenty of water can remain despite tilling of the subsoil by meteors.

Water in the air will frost out, be covered by dust, be absorbed into salts and other minerals that can be hydrated, etc. Also every water molicule that breaks up does not mean the hydrogen is lost at once. A hydrogen ion is very reactive, there is a good chance that something else will grab the naked proton before it gets a chance to be lost to space.

Lastly, small amounts of hydrogen get absorbed by the atmosphere. Mars has a tiny amount of free O2 in its air.
(About 0.001 Pa partial pressure if I remember right.) Some of the solar wind might react with this O2 (the exosphere is hot enough) and this would form more water.

(Does anyone have any idea how much the rate of hydrogen - solar - wind - capture would speed up if there was more O2 in the Martian atmosphere? Is this effect at all significant? Most discussions ignore it but I see no reason why it could not happen.)

I suspect (this is musing on my part) that water & ice crystals are more immune to break up by UV. If the UV dissassociates a hydrogen from H2O in ice, the proton is trapped by the ice crystal. The ice will form H3O+ and OH- (hydronium and hydroxide ions) which remain in the crystal and will eventually neutralize each other. Ditto for water.

Earth has lost quadrillions of tonnes of water to UV light. People estimate that Earth has lost about a meter of water from its oceans per 1 billions years to this cause. (The slow rate of this process on Earth is largely because of the 'cold trap' that keeps most of the H2O away from the most powerful UV radiation.)

Lastly remember that Mars gets about 1/2 the UV light that Earth does. The process will happen slower on Mars.

Warm regards, Rick.

nickname · 2007-04-09 10:37:03

Rick,

Same catch 22 though, if Mars is slow to break apart frozen h20 and the soil is an amazing sponge for 02, then we should have no frosts at all.

The best guess is that the poles have been in existence at least 500 million years, so the soak up time for the top layers of soil should be long done even at very slow release rates.

The color of the soil seems right for a planet slowly loosing its store of water ice to Hydrogen and free 02.
The color of the soil also seems to state that a lot of free 02 has been soaked up.

If it is similar to the losses on earth then we should see a snow cover on Mars and much higher quantities of free 02 and cloud in the atmosphere.

Maybe the extra UV makes the ice loss similar to the earths liquid water losses.
Mars being higher in UV but tougher to break bonds, Earth h20 being easier to break bonds but much better protected from UV.

Are we just lucky to be at a time when Mars has finished being a sponge and will start being a snow and heavy frost covered place?
Does the solar wind cause some strange chemistry at Mars?
Is Mars ice mostly frozen C02 ,or large quantities of H20 ice protected with thin C02 ice?
Do the extra other high energy radiations have a role in making Mars chemistry unusual.?
Or some unexpected mechanics happening we don't quite understand?
Or like you say the chemistry at Mars allows free hydrogen to re bond back into h20 frost that slowly accumulates on the poles.
All rhetorically questions..........

Mars is trying to tell us something about itself

RickSmith · 2007-04-09 21:40:20

Hi nickname,
From my readings I think that the situation is that some time ago (say 1,000,000 years ago) Mars was such that ice was stable at 40 degrees of latitude. Now things have changed so that the ice is subliming / melting at 40 degrees. Some of it seeps deeper into the soil and refreezes. Some evaporates and is deposted as frost all over the place. If it does so north of (say) 43 degrees it is stable for a long time. If it freezes at midnight at the equator, then around 2:00 pm it is likely to be in the air again looking for some place else to freeze out.

There is a fair bit of evidence that ice is melting in many places on Mars.

Regards, Rick.

nickname · 2007-04-10 07:39:28

Hi Rick,

Yes it's very interesting to see all those new pictures from Mars with what looks like mini canals from small melts.

It's a very hot topic right now and seems like no one has a consences on what the fluid could be.

I wonder if its some strange form of heavily carbonated water ice or geysers is the culprit.
The Martian temperatures work pretty well for heavily carbonated water ice melts and freezes, but how could Mars make such an irregular ice?
Carbonated water should persist long enough to make the channels but evaporate away leaving no pools.

I can't think of what else it could be on Mars unless it's very salty water ice geysers, even that is suspect for the temperature and duration of the events.

RickSmith · 2007-04-10 17:28:38

Hi all,
My understanding is that there is snow covered with dust. In the summer it melts under the snow. The water runs out and rapidly evaporates. However it lasts long enough to make a gully 150 meters long.

Warm regards, Rick.

New Mars Forums

Announcement

#1 2006-12-12 10:43:49

Re: Mars getting pounded

#2 2006-12-13 17:37:15

Re: Mars getting pounded

#3 2006-12-14 05:12:16

Re: Mars getting pounded

#4 2006-12-14 12:13:19

Re: Mars getting pounded

#5 2006-12-14 12:54:44

Re: Mars getting pounded

#6 2006-12-15 05:16:05

Re: Mars getting pounded

#7 2007-03-03 03:58:36

Re: Mars getting pounded

#8 2007-03-03 05:38:16

Re: Mars getting pounded

#9 2007-03-03 14:33:27

Re: Mars getting pounded

#10 2007-03-03 18:09:56

Re: Mars getting pounded

#11 2007-03-03 18:26:30

Re: Mars getting pounded

#12 2007-03-04 07:28:15

Re: Mars getting pounded

#13 2007-03-04 14:05:00

Re: Mars getting pounded

#14 2007-03-17 03:44:23

Re: Mars getting pounded

#15 2007-03-17 07:39:34

Re: Mars getting pounded

#16 2007-04-08 05:14:01

Re: Mars getting pounded

#17 2007-04-08 07:58:00

Re: Mars getting pounded

#18 2007-04-09 01:50:52

Re: Mars getting pounded

#19 2007-04-09 10:37:03

Re: Mars getting pounded

#20 2007-04-09 21:40:20

Re: Mars getting pounded

#21 2007-04-10 07:39:28

Re: Mars getting pounded

#22 2007-04-10 17:28:38

Re: Mars getting pounded

Board footer